1. Field of the Invention
The invention relates to a machine for producing a continuous material web, as well as a belt for use in such a machine.
2. Discussion of Background Information
Machines and belts of the type discussed here are known. In known machines of this type, for example paper machines, the drive is effected in different manners in different sections, for example, in forming, press and/or drying sections. It is possible, for example, to set (drying) screens and felts into motion by using several driven rolls. It is possible thereby to connect drive devices, that is, motors or the like, directly to the rolls, or by way of gears. A disadvantage of using gears is the high noise level. A further option is to drive the rolls by way of pulleys mounted to the end faces. In this case, a motor can also set several rolls in rotation.
It is also possible to couple several rolls or drying cylinders of a group to one another by way of toothed wheels, and to use, for example, one motor per group. While this solution provides good synchronization, it is associated with a sustained high noise level. The costs to produce the machine drive also increase.
Another observed drawback is that the belts forming an endless loop and having a circumference of 20 to 30 m or more, for example, must absorb the entire drive force, and are subjected to expansion. This has a negative impact on the production of the material web. It is possible that the material web, for example a paper web, be correspondingly expanded as the belt expands, or relative movements may occur between the belt and the material web. Both phenomena adversely affect the properties of the material web. It is possible to reduce these negative influences by using several drives for one belt. This approach, however, increases the costs for the machine. In addition, it is necessary to employ control and/or regulating devices for attaining an exact match of speeds between the drives.
Particularly early on, belt drives were also realized; these, however, were distinguished by large spatial requirements due to the necessary protective covers. Furthermore, the accessibility to the machine is impeded especially when several rolls are driven by way of transmission belts.